Thread controlling device



Get. 29, 19:46., W 2,410,400

THREAD CONTROLLING DEVICE Filed June '15, 1945 Patented Get. 29. 1946 THREAD CONTROLLING DEVICE Alfred R. Wood, Bridgeport, Conn, assignor to The Singer Manufacturing Company, Elizabeth, N. .F'., a corporation of New Jersey Application June 15, 1945, Serial No. 599,584

Claims.

This invention relates to sewing machines and more particularly to an improved device for controlling the sewin machine needle-thread.

More specifically this invention relates to slack thread controlling devices and it has for an object to provide an improved means affording a more sensitive and accurate control over the needle-thread.

Another object of the invention is to provide needle-thread controlling mechanism which may be readily adjusted and easily threaded.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawing of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

Fig. 1 is a left side elevation of a sewing machine bracket-arm head embodying the invention.

Fig. 2 is a fragmentary front elevation of the bracket-arm head.

Fig. 3 represents an enlarged sectional elevation of the thread-controlling mechanism; the section being taken substantially along line 3--3 of Fig. 1.

Fig. 4 represents a cross sectional view of the thread controlling device taken substantially along line 4-4 of Fig. 3.

In the specific embodiment of the invention chosen for the purposes of the present disclosure, 1 represents a sewing machine bracket-arm which terminates in the hollow bracket-arm head 2 in which is journaled the usual reciprccatory needle-bar 3. The lower end portion of the needlebar carries the usual needle l and the upper portion thereof has a take-up arm 5 associated therewith.

Mounted upon the bracket-arm head 2 is the usual releasable type tension unit 6 having the spring biased disks 7 and 8.

Secured to the head 2 by means of a screw 9 is a mounting bracket H) which is provided with an aperture II for slidably receiving a vertically depending post 12 of the present improved thread controlling device or thread-check. A screw l3 provides for vertical adjustment of the post I2 within the aperture I l.

This thread-check comprises the post l2 of which the lower portion is provided with a split two-part circular abutment flange or stop I l-I l. The face portions or thread-guiding means |5-l 5 of this flange are inclined upwardly toward a thread-slot it provided longitudinally of the post l2. By thus inclining the faces 15, a thread may be more easily introduced into the slot it. Mounted upon the post I2 is a spring-abutment collar ll which may be vertically adjusted by means of the screw I8.

Confined between the collar ii and the flange M is a check-spring Ill, the lower end portion of which embraces a thread-engaging collar or guide 213. The spring l9 may be soldered or otherwise secured to the collar 20. The post I? is formed with four substantially fiat faces 2i for the purposes of reducing friction between the post l2 and the spring and collar assembly l9 and 29.

In order to avoid nipping the thread between the flange I l and the collar 20 during the operation of the device, the flange has been provided with 'the upwardly extending portions 22 which prevent the collar 2c from seating in a flush relation with the remainder of the flange, thus to provide adequate clearance space for the thread.

To properly operate the present improved device, the needle-thread 23 is brought from its usual supply source, not herein shown, to be first threaded through the ironing guide 24 from whence it is led between the tension disks 1 and 8. From the tension device 5 the thread is carried up over the stationary guide-wire 2 5, through the thread-slot l6 and then successively about the guide-wire 26, through the take-up eye 21, through the guides 28 and 29, and finally through needle-bar eye 36 to the needle l.

A wire guard 3| is preferably positioned to extend about the lower portion of the thread-check.

As may be best seen from Fig. 1, the thread guides 25 and 26 are positioned at opposite sides of the thread-check and at points abovethe normal or extended position of the thread-check, so that each guide will position the thread carried thereby at an acute angle to the axis of the thread-check. As the thread is thus positioned at an acute angle relative to this axis, it will be readily understood that little tension will be required in the thread in order to raise the collar 29 against the spring 19.

It is the purpose of the present thread-check to function as an auxiliary needle-thread takeup in that it is adapted to take up any slack thread which the take-u arm 5 is unable properly to control. In order to accomplish this function, the spring [9 must apply substantially less tension upon the thread than does the tension unit 6. Therefore, whenever the take-up arm 5 toward saidstep.

3 pulls thread through the tension unit 5, it must exercise more than enough tension on the thread to raise the collar 2;} against spring 19. Thereafter in the event that the take-up 5 permits any slack to exist in the thread, the elevated collar 29 will descend under the action of spring 19 and control the thread. As the spring [9 is relatively long as compared to its diameter, it will exert a substantially constant tension upon the thread throughout the entire range of the unit; which range is governed by the relative vertical spacing between the lowest position of the collar 20 and the thread-guides 25 and 25. This spacing may be varied by adjusting the post 12 within the bracket it. The tension of the spring i3 may be varied by adjusting the collar i? along the post i2.

It Will be readily understood that the present. reciprocable thread-check will permit a greater amplitude of thread movement without appreciably increasing the tension in the thread than if the usual type of short torsion spring were used.

It will be seen that the present device comprises an efiective unit for controlling a needle- 0 thread in cooperation with the usual tension and take-up devices. device is of simple construction, inexpensive to manufacture and it may be readily installed on the standard type of sewing machine.

Having thus set forth the nature of the invention, what I claim herein is:

l. A yielding thread-guide for sewing machines comprising amountingmeans, a post having one end portion thereof carried by said mounting means and being provided with a transverse thread-slot extending longitudinally throughthe other end portion of said post, a thread-engaging element'freely slidable endwise of said post, a stop associated with the slotted end of the post, and spring means carried by said post for urging said thread-engaging means 2; A yielding thread-guide forsewing machines comprising a mounting means,- a-post having one endpo'rtion thereof carried by said mounting means and being provided with a transverse thread-slot extending longitudinally through the other end portion of said-post,- thread-guiding means associated with said thread-slot and posi- Furthermore, the present 4 tioned at the slotted end of said post, a threadengaging element freely slidable endwise of said post, a stop associated with the slotted end of the post, and a coil spring carried by said post for urging said thread-engaging means toward said stop.

3. A yielding thread-guide for sewing machines comprising a mounting means, a post having one end portion thereof carried by said mounting means and being provided with a transverse thread-slot extending longitudinally through the other end portion of said post, thread-guiding means associated with said thread-slot and positioned at the slotted end of said post, a collar adjustably' secured to the post adjacent the mounted end thereof, a stop carried by the slotted end of said post, a, thread-engaging collar freely slidable on the post, and a coil-spring positioned between said collar and said threadengaging collar for urging the latter toward said stop.

4.111 a sewing machine, in combination, a reciprocatory thread-carrying needle, a needlethread take-up, a needle-thread tension device disposed at the thread-supply side of said takeup, a vertically depending post having a longitudinal thread-guiding slot open at the lower end of the post, a thread-engaging member confined for movement lengthwise of said post and disposed for engagement by a portion of the needlethread extending from said tension-device to said take-up, and an elongate coil-spring confined by said post and yieldingly biasing said thread engaging member downwardly. 1

5. In a sewing machine, in combination, a reciprocatory thread-carrying needle, a needlethread take-up, a needle-thread tension device disposed at the thread-supply side of said takeup, a vertically depending post having a longitudinal thread-guiding slot open at the lower end of the post, a thread-engaging member confined for movement lengthwise of said post and disposed for engagement by a portion of the needlethread extending from said tension-device to said take-up, an elongate coil-spring confined by said post and yieldingly biasing said threadengaging member downwardly, and-stop means limiting downward movement of said thread engaging member.

r r ALFRED R WOOD. 

